1. Field of the Invention
The present invention relates to an electroluminescent device, and more particularly, to an active matrix electroluminescent device and a method for fabricating the same.
2. Discussion of the Related Art
An electroluminescent device is being viewed as a next generation flat display device for its characteristics of a wide viewing angle, a high aperture ratio, and a high chromaticity. More specifically, in an organic electroluminescent (EL) device, when an electric charge is injected into an organic luminescent layer formed between a hole injection electrode and an electron injection electrode, the electron and the hole are paired to each other generating an exciton, the excited state of which falls to a ground state, thereby emitting light. Thus, the organic electroluminescent device (ELD) can be operated at a lower voltage, as compared to other display devices.
Depending upon the driving method, the organic ELD can be classified into a passivation ELD and an active matrix ELD. The passivation ELD is formed of a transparent electrode on a transparent substrate, an organic EL layer on the transparent electrode, and a cathode electrode on the organic EL layer. The active matrix ELD is formed of a plurality of scan lines and data lines defining a pixel area on a substrate, a switching device electrically connecting the scan lines and the data lines and controlling the electroluminescent device, a transparent electrode electrically connected to the switching device and formed in the pixel area on the substrate, an organic EL layer on the transparent electrode, and a metal electrode on the organic EL layer. Unlike the passivation ELD, the active matrix ELD further includes the switching device, which is a thin film transistor (TFT).
However, the related art active matrix ELD is disadvantageous in that the thin film transistor causes a decrease in the aperture ratio and the luminous efficiency of the device. An expansion of the pixel area is required in order to enhance the aperture ratio and the luminous efficiency. However, there are limitations to such expansion. More specifically, an excessive expansion of the pixel area causes deficiency in the functions of the thin film transistor, the counter electrode, and the metal electrode.